Heat Transfer in a Disc-Type DSC Apparatus IV. Applicability of the coupled cells model to periodic temperature modulation |
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Authors: | Claudy P Letoffe J M |
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Institution: | (1) Laboratoire des Matériaux Organiques à Propriétés Spécifiques UPR CNRS 9031, BP 24, 69390 Vernaison;(2) ESA 5079 CNRS Energétique et synthèse inorganique INSA, Bat 401, 20 avenue A. Einstein, 69621 Villeurbanne Cedex, France |
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Abstract: | The application of non-linear heating programs to a heat-flux DSC apparatus has attracted much attention. On the basis of
thermodynamics, the change in enthalpy of a sample during a temperature change ΔT is due, on the one hand to the true heat
capacity of the sample ΔT Cpξ and on the other, to the enthalpy of some transformation occurring in the sample ΔrH Δξ. These contributions can be separated on the basis of the kinetics of the transformation. The coupled cells model of
a disc type, heat flux DSC apparatus has been tested, using true heat capacities and a sine modulation of the temperature
of the furnace around a constant temperature. In the range from 2 to 60 mHz, the amplitude and phase shift of the calorimetric
signal were measured at several frequencies. Theoretical equations, based on the model, and using the thermal Ohm's law explains
the results with a reasonable accuracy. A non-linear DSC experiment affords two ways of determination of the heat capacity
of a sample making possible a distinction between the enthalpic effect and heat capacity.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | DSC (temperature modulated DSC) frequency response modelling of DSC phase shift response thermodynamic discussion of DSC |
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